A sensitive x-ray phase contrast technique for rapid imaging using a single phase grid analyzer

Abstract

Phase contrast x-ray imaging (PCXI) is a promising imaging modality, capable of sensitively differentiating soft tissue structures at high spatial resolution. However, high sensitivity often comes at the cost of a long exposure time or multiple exposures per image, limiting the imaging speed and possibly increasing the radiation dose. Here, we demonstrate a PCXI method that uses a single short exposure to sensitively capture sample phase information, permitting high speed x-ray movies and live animal imaging. The method illuminates a checkerboard phase grid to produce a fine grid-like intensity reference pattern at the detector, then spatially maps sample-induced distortions of this pattern to recover differential phase images of the sample. The use of a phase grid is an improvement on our previous absorption grid work in two ways. There is minimal loss in x-ray flux, permitting faster imaging, and, a very fine pattern is produced for homogenous high spatial resolution. We describe how this pattern permits retrieval of five images from a single exposure; the sample phase gradient images in the horizontal and vertical directions, a projected phase depth image, an edge-enhanced image, and a type of scattering image. Finally, we describe how the reconstruction technique can achieve subpixel distortion retrieval and study the behavior of the technique in regard to analysis technique, Talbot distance, and exposure time.

State of the Art of X-ray Speckle-Based Phase-Contrast and Dark-Field Imaging

“…This was demonstrated with a 1D periodic phase grating [148], a 2D attenuation grid [149] and a 2D phase grid [150]. In contrast to the above mentioned grid method by Wen et al [147], this approach enables quantitative single-shot imaging of objects with features similar or smaller than the grid pitch as well as objects larger than the field of view.…”

“…As mentioned in the previous section, this approach can be seen as a generalisation of single-shot 2D grid-based methods [149,150] to a random interference pattern.…”

In Vivo X-Ray Imaging Reveals Improved Airway Surface Hydration after a Therapy Designed for Cystic Fibrosis

“…At the image detector, the grid will appear distorted according to the refractive properties of the airway tissue, in the same way the tile pattern on the bottom of a swimming pool will appear distorted according to the refractive properties of the water (10). By analyzing these distortions, we can quickly and sensitively produce an image of the ASL (6)(7)(8).…”

X-ray phase contrast tomography by tracking near field speckle

“…This translates in a reduction in the correlation value between the reference and target subsets. This approach is fully equivalent in principle to scattering properties mapping29, where the correlation amplitude and tracking is calculated from a regular grid pattern rather than here a random speckle pattern.…”